I'm using WinRar trying to unpack a series of rar files - I begin with -000 and it stops with the message when unpacking the next -001, that there is another file by that name and do I overwrite it. So what do I need to do to unpack the rest. ANY help would be appreciated - thanks

Then that is a split file which you will note has the same size for each "chunk". The actual file within is just 1 single file, split and packaged within multiple zips. Your application should sequentially unzip and rebuild the file. You cannot just unzip each chunk separately.

Depends where the file was downloaded from and how it was split as to how you would unzip on your end. 7zip should work with anything at all and is free.